1. Field of the Invention
The present invention relates to fluid-conveying apparatuses and methods for conveying fluid using the same. Specifically, the present invention relates to fluid-conveying apparatuses suitable for micro-analysis systems (μ-TAS: Micro-total analysis system) for performing chemical analysis or chemical synthesis on chips.
2. Description of the Related Art
Recently, as stereo-microprocessing technology has been developed, a so-called micro-analysis system, μ-TAS (Micro-total analysis system), or Lab on a Chip has been developed. These systems have elements for conveying fluid, i.e., a channel, a pump, and a valve, and in addition have a sensor. The elements and the sensor are integrated on a substrate of glass, silicon, or the like, and chemical analysis is performed on the substrate. By miniaturizing the chemical analysis system, void volumes can be decreased and the sample amounts required for analysis can be significantly decreased. Furthermore, reduction in analysis time and lower power consumption of the whole system can be achieved. Additionally, price-reduction of the system can be expected by the miniaturization. Thus, in the μ-TAS, the miniaturization of the system, price-reduction, and a large reduction in analysis time are possible, so the μ-TAS is expected to be applied to medical fields, such as home medical care and bedside monitoring, and biotechnological fields, such as DNA analysis and proteome analysis.
In the above-mentioned μ-TAS, various constitutions of valves have been suggested in order to control the fluid flow in the microchannel. Water repellent finishing of a surface of the microchannel can increase the surface tension of the fluid. By utilizing these features, a valve being capable of terminating the fluid flow until the pressure applied to the fluid reaches a predetermined value has been realized (U.S. Pat. No. 6,296,020 B1). Furthermore, Japanese Patent Laid-Open No. 2003-270252 discloses a microchannel provided with a wax-type valve wherein the fluid flow is controlled by heating the valve from the outside of the microchannel. With such valves, a hydraulic circuit being capable of performing a plurality of processes by a simple constitution can be composed by utilizing electrophoresis or centrifugal force as a driving source. Such a hydraulic circuit can reduce the system size as a whole, even if the scale of the hydraulic circuit itself is increased.
However, the valve utilizing the surface tension of fluid and the wax-type valve are poor in terms of pressure resistance. Therefore, when a high-pressure pump is used as a fluid-conveying means, leakage or breakage of the valve may possibly occur resulting in it being difficult to precisely control the fluid flow.